Effects of Plant Growth Substances on Biomass and Lipid Production in Diatoms

Abstract

The effects of plant growth stimulating substances like naphthalene-acetic acid (NAA), Gibberellic acid 3 (GA 3 ) and 6-benzylaminopurine (6-BA), or plant growth inhibiting substances like abscisic Acid (ABA) and ((2-chloroethyl) trimethylammonium chloride) (CCC), or their combinations, on biomass and lipid production in Pinnularia gibba var. linearis and Chaetoceros gracilis were studied. When applied at day 1 (stage I), treatments with NAA, GA 3 and 6-BA or their combinations enhanced biomass production but reduced lipid contents. The total lipids, however, were higher in these treatments than that in the control. 6-BA was more effective in stimulating total lipid production. No difference was found among the treatments with NAA, GA 3 or their combination. Adding NAA or GA 3 to 6-BA did not enhance biomass or lipid production compared with 6-BA alone. When applied at day 4 (stage II), growth stimulating substances increased biomass production compared with the control but did not affect total lipid production. Less biomass was obtained when the treatments were applied at day 4 compared with that applied at day 1. Treatments with growth inhibitors like ABA, CCC or ABA + CCC at day 1 reduced biomass production and total lipids, although lipid contents were increased by the treatments. When treated with ABA, CCC and ABA + CCC at day 4 , however, they did not reduce biomass production while increased lipid contents and total lipids.